Chlamydiaceae is a family of obligate intracellular parasites. All members share a common developmental cycle. Chlamydia infect a wide range of vertebrate host, particularly humans. Chlamydia trachomitis is one of the two recognized species of Chlamydia. Human infections caused by Chlamydia trachomitis are widespread. This species is one of the most common cause of sexually transmitted disease in the world. It is also one of the main causes of infertility in humans.
The frequency of Chlamydia trachomatis infections has risen dramatically in the past 20 years. This has been attributed to the emergence of multiply antibiotic resistant strains and an increasing population of people with weakened immune systems. It is no longer uncommon to isolate Chlamydia trachomatis strains which are resistant to some or all of the standard antibiotics. This has created a demand for both new anti-microbial agents and diagnostic tests for this organism.
Aminoacyl-tRNA synthetases (aaRS) catalyze the ligation of amino acids to their cognate tRNA species in all cellular organisms. In general, each of the twenty amino acids that are incorporated into growing polypeptide chains has a corresponding aaRS. However, it is now well documented that this is not universally true and that glutaminyl-tRNA synthetase (QRS) activity is absent in all Gram-positive prokaryotes examined, in some Gram-negative prokaryotes and in the plastids of some, and possibly all, eukaryotes. Despite the absence of glutaminyl-tRNA synthetase activity, cells are clearly able to produce the Gln-tRNAGln required for accurate protein synthesis. The mechanism by which this is achieved involves the formation of Glu-tRNAGln as an intermediate that is produced by the misaminoacylation of tRNAGln by glutamyl-tRNA synthetase (ERS). The "correct" end product, Gln-tRNAGln, is formed from Glut-RNAGln by transfer of an amine group to the ligated glutamate residue. This reaction is catalyzed by a tRNA- and Mg2+/ATP-dependent amidotransferase (RNA-dependent AmidoTransferase-RAT). Inhibition of this apparently ubiquitous reaction in Gram-positive organisms, and some Gram-negative organisms, would effectively lead to Gln-tRNAGln starvation and to the synthesis of aberrant proteins and the consequent cessation of bacterial protein synthesis.
Clearly, there is a need for factors, such as the novel compounds of the invention, that have a present benefit of being useful to screen compounds for antibiotic activity. Such factors are also useful to determine their role in pathogenesis of infection, dysfunction and disease. There is also a need for identification and characterization of such factors and their antagonists and agonists which can play a role in preventing, ameliorating or correcting infections, dysfunctions or diseases.
The polypeptides of the invention have amino acid sequence homology to a known PET112-type protein from Synechocystis sp. PCC6803, encoded by a nucleotide sequence contained with the sequence defined by Genbank Accession number D90913.